Instruments for positioning and installing acetabular cup assemblies into hip bones are well known in the field of orthopedic medicine. Conventional prosthetic cup assemblies include a semi-spherical outer cup or shell and a polymer bearing liner. The shell is positioned and seated into the acetabulum of a patient by an impactor which is used to seat the shell into the prepared acetabulum. Typically, the shell is temporarily secured to the distal end of an impactor. Mounting the shell to the impactor allows the shell to be easily aligned and securely positioned as the impactor is used to seat the shell into the acetabulum. Once the shell is securely seated in the acetabulum, the impactor is disconnected and the liner is fitted to the shell. While the liner generally snaps into the shell, a separate instrument occasionally may be required to insert the bearing liner into the shell. The additional instrument used to seat the bearing liner adds to the total instrument count in the surgical procedure.